WO2005057697A2 - Empilement de piles a combustible - Google Patents

Empilement de piles a combustible Download PDF

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Publication number
WO2005057697A2
WO2005057697A2 PCT/JP2004/017892 JP2004017892W WO2005057697A2 WO 2005057697 A2 WO2005057697 A2 WO 2005057697A2 JP 2004017892 W JP2004017892 W JP 2004017892W WO 2005057697 A2 WO2005057697 A2 WO 2005057697A2
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WO
WIPO (PCT)
Prior art keywords
region
fuel cell
cell stack
gas
gas diffusion
Prior art date
Application number
PCT/JP2004/017892
Other languages
English (en)
Other versions
WO2005057697A3 (fr
Inventor
Atsushi Ohma
Original Assignee
Nissan Motor Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nissan Motor Co., Ltd. filed Critical Nissan Motor Co., Ltd.
Priority to US10/582,222 priority Critical patent/US20070105001A1/en
Priority to DE112004002438T priority patent/DE112004002438T5/de
Priority to CA2548296A priority patent/CA2548296C/fr
Publication of WO2005057697A2 publication Critical patent/WO2005057697A2/fr
Publication of WO2005057697A3 publication Critical patent/WO2005057697A3/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
    • H01M8/026—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant characterised by grooves, e.g. their pitch or depth
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8605—Porous electrodes
    • H01M4/861—Porous electrodes with a gradient in the porosity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
    • H01M8/0265—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant the reactant or coolant channels having varying cross sections
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0267—Collectors; Separators, e.g. bipolar separators; Interconnectors having heating or cooling means, e.g. heaters or coolant flow channels
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
    • H01M8/2418—Grouping by arranging unit cells in a plane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/2457—Grouping of fuel cells, e.g. stacking of fuel cells with both reactants being gaseous or vaporised
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/2465—Details of groupings of fuel cells
    • H01M8/2483—Details of groupings of fuel cells characterised by internal manifolds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • This invention relates to a fuel cell stack comprising a plurality of stacked unit cells.
  • the rib width of a separator on the fuel gas side is made narrower at the downstream side of the fuel gas to even out the current density distribution over the surface of each unit cell. Further, considering that gas diffusion is worse on the oxidant gas side, which uses oxygen, than the fuel gas side, which uses hydrogen, in JP8-203546A, published by the Japan Patent Office in 1996, the rib width of a separator on the oxidant gas side is made narrower than the rib width on the fuel gas side.
  • this invention provides a fuel cell stack comprising a plurality of stacked unit cells, wherein each unit cell comprises: a membrane electrode assembly in which a gas diffusion electrode is disposed on each side of a polymer electrolyte membrane; and a separator comprising a plurality of ribs which contact the membrane electrode assembly to realize a current collecting function, and a plurality of gas passages formed between the ribs for supplying a gas to the gas diffusion electrode, the fuel cell stack comprises a first region and a second region in the interior thereof, the first region having a higher temperature than the second region, and at least one of the gas passages, the ribs, and the gas diffusion electrode is constituted such that a gas diffusion through the gas diffusion electrode adjacent to the first region
  • FIG. 1A is a schematic diagram of a unit cell in a fuel cell stack of this invention.
  • FIG. IB is a plan view of an oxidant gas separator used in the unit cell.
  • FIG. 2 is similar to FIG. IB, but shows a second embodiment of this invention.
  • FIG. 3 is a rear view of an oxidant gas separator used in the second embodiment.
  • FIG. 4 is a plan view of an oxidant gas diffusion electrode used in a third embodiment.
  • FIG. 5 is similar to FIG. IB, but shows the third embodiment of this invention.
  • FIG. 6 is similar to FIG. IB, but shows a fourth embodiment of this invention.
  • FIG. 7 is a side view of a fuel cell stack in a fifth embodiment.
  • FIG. 8 is similar to FIG. IB, but shows a sixth embodiment of this invention.
  • FIG. 1A shows an outline of the constitution of a unit cell 11 in a fuel cell stack 10 according to this invention.
  • the unit cell 11 is constituted by a membrane electrode assembly la in which gas diffusion electrodes lp are disposed on each side of a polymer electrolyte membrane lm, and an oxidant gas separator lb and a fuel gas separator lc disposed on each side of the membrane electrode assembly la.
  • the fuel cell stack 10 is constituted by a plurality of the unit cells 11 stacked together.
  • FIG. IB shows the constitution of the oxidant gas separator lb.
  • the separator lb is manufactured from a conductive carbon resin composite.
  • the separator lb is formed with fuel gas manifolds 2a, 3a, oxidant gas manifolds 2b, 3b, and coolant manifolds 2c, 3c serving as passages allowing fuel gas, oxidant gas, and coolant to flow respectively in the stacking direction of the fuel cell stack 10.
  • Each manifold serves as either a fluid supply manifold or a fluid discharge manifold.
  • the separator lb is provided with a plurality of oxidant gas passages 4b bifurcating from the oxidant gas supply manifold 2b and extending to the oxidant gas discharge manifold 3b.
  • Ribs 5b having a convex cross section and contacting the gas diffusion electrode lp to realize a current collecting function are provided between the passages 4b.
  • the passages 4b increase gradually in width from the end parts of the surface of the separator lb toward the center. If it is assumed that the central region on the cell surface of the unit cell 11 when the fuel cell stack 10 is viewed from the stacking direction is a first region, and the region on the outside thereof is a second region, then the temperature of the first region is higher than the temperature of the second region. In this embodiment, the width of the passages 4b adjacent to the first region is greater than that of the passages 4b adjacent to the second region, and hence these passages 4b have a greater sectional area.
  • the width of the passages 4b increases gradually toward the inside of the cell surface, but the width may be increased in stages several passages at a time. Further, the reason for altering the width of the passages 4b is to increase the sectional area of the passages 4b, and therefore instead of, or in addition to, altering the width of the passages 4b, the depth of the passages 4b may be altered. Moreover, a similar constitution may be applied to the fuel gas side as well as the oxidant gas side.
  • FIG. 2 shows the constitution of the oxidant gas separator lb used in the unit cell 11 of a second embodiment.
  • the basic constitution of the unit cell 11 is identical to that shown in FIG. 1A. Shared constitutions with the first embodiment have been allocated identical reference numerals, and description thereof has been omitted.
  • the oxidant gas separator lb is manufactured from a conductive carbon resin composite.
  • the separator lb is formed with fuel gas manifolds 2a, 3a, oxidant gas manifolds 2b, 3b, and coolant manifolds 2c, 3c allowing fuel gas, oxidant gas, and coolant to flow respectively in the stacking direction of the fuel cell stack 10.
  • Each manifold serves as either a fluid supply manifold or a fluid discharge manifold.
  • the oxidant gas separator lb is provided with a plurality of oxidant gas passages 4b bifurcating from the oxidant gas supply manifold 2b and extending to the oxidant gas discharge manifold 3b.
  • Ribs 5b having a convex cross section and contacting the gas diffusion electrode lp to realize a current collecting function are provided between the passages 4b.
  • the width of the ribs 5b decreases in stages from the lower part of the separator surface in the drawing toward the upper part.
  • FIG. 3 shows a rear view of the oxidant gas separator lb shown in FIG. 2.
  • Coolant is introduced into coolant passages 4c from the coolant inlet manifold 2c, and discharged to the outside of the fuel cell stack 10 from the coolant discharge manifold 3c.
  • the region where the ribs 5b of the oxidant gas separator lb are narrow (the upper part of FIG. 2) is disposed on the rear of the downstream side of the coolant passages 4c.
  • the temperature of the coolant and the gas diffusion electrode lp is highest on the downstream side of the coolant passages 4c.
  • the region near the outlet from the coolant passages 4c is a first region
  • the region on the outside of the first region is a second region
  • the temperature of the first region is higher than that of the second region.
  • the ribs 5b provided on the oxidant gas separator lb decrease in width from the lower part to the upper part of the surface of the separator lb, and therefore the width of the passages 4b adjacent to the first region is greater than the width of the passages 4b adjacent to the second region.
  • temperature distribution over the cell surface is uneven such that the temperature in the downstream region of the coolant passages 4c is high.
  • This surface temperature differential of the gas causes differences to arise in the expansion factor and saturation vapor pressure, leading to a reduction in the mass flow of the oxidant gas flowing in the upper part of the oxidant gas separator lb. This tendency is particularly striking in high current density regions.
  • the width of the ribs 5b decreases at the upper part of the oxidant gas separator lb, as described above, and hence in the part of the gas diffusion electrode lp which overlaps the upper part of the oxidant gas separator lb, the area of surface contact with the oxidant gas increases.
  • the gas diffusion is improved, and reductions in the gas diffusion can be suppressed even when the mass flow of the oxidant gas decreases.
  • reductions in current density caused by a decrease in the mass flow of the gas in the high temperature regions of the cell surface are suppressed, and thus a fuel cell stack exhibiting stability and high performance can be obtained even under operating conditions such as high current density, where diffusion limiting is likely to occur.
  • the width of the ribs 5b decreases in stages, but the width of the ribs 5b may be reduced gradually toward the upper part of the oxidant gas separator lb. Further, a similar constitution may be applied to the fuel gas side as well as the oxidant gas side. Moreover, other than reducing the width of the ribs 5b, the ribs 5b may be formed in a lattice form or the like to reduce the surface area of the ribs 5b contacting the gas diffusion electrode lp. Further, the coolant passages 4c are provided on the rear surface of the oxidant gas separator lb, but instead, a cooling plate may be disposed adjacent to the oxidant gas separator lb and coolant passages may be provided in the cooling plate.
  • FIG. 4 shows the constitution of the oxidant gas diffusion electrode lp used in a fuel cell stack of a third embodiment.
  • the basic constitution of the unit cell 11 is identical to that shown in FIG. 1A. Shared constitutions with the first embodiment have been allocated identical reference numerals, and description thereof has been omitted.
  • the oxidant gas diffusion electrode lp is constituted by coating the surface of carbon paper with a mixture of carbon powder supporting a platinum catalyst and an electrolytic solution.
  • the outer form of the oxidant gas diffusion electrode lp is approximately identical to the range of the gas passages 4b provided in the oxidant gas separator lb. As shown in FIG.
  • a part of the surface of the carbon paper is coated with a mixture of carbon and Teflon before being coated with the mixture of carbon powder supporting a platinum catalyst and the electrolytic solution.
  • a region A which is not coated with the carbon-Teflon mixture is disposed in the upper region of the oxidant gas diffusion electrode lp, and overlaps the downstream side region of the coolant passages 4c where the temperature is highest.
  • the membrane electrode assembly la employing this oxidant gas diffusion electrode lp, the fuel gas separator lc, and the oxidant gas separator lb shown in FIG. 5 are stacked together to form the unit cell 11. In the oxidant gas diffusion electrode lp shown in FIG.
  • the region A (the upper part of the drawing), constituted by carbon paper alone and not coated with the carbon-Teflon mixture, has a greater average porosity in the direction of thickness than a coated region B, and hence the oxidant gas diffusion is better in the region A.
  • temperature distribution over the cell surface is uneven such that the temperature in the downstream region of the coolant passages is high.
  • This surface temperature differential of the gas causes differences to arise in the expansion factor and saturation vapor pressure, leading to a reduction in the mass flow of the oxidant gas flowing in the upper part of the oxidant gas separator lb. This tendency is particularly striking in high current density regions.
  • the gas diffusion is improved by increasing the average porosity in the upper part of the gas diffusion electrode lp adjacent to the oxidant gas separator lb.
  • reductions in current density accompanying a decrease in the mass flow are suppressed, and a fuel cell stack exhibiting stability and high performance can be obtained even under operating conditions such as high current density, where diffusion limiting is likely to occur.
  • the oxidant gas diffusion electrode was cited, but a similar constitution may be applied to the fuel gas diffusion electrode.
  • FIG. 6 shows the constitution of the oxidant gas separator lb used in the fuel cell stack 11 according to a fourth embodiment.
  • the basic constitution of the unit cell 11 is identical to that shown in FIG. 1A. Shared constitutions with the first embodiment have been allocated identical reference numerals, and description thereof has been omitted.
  • the separator lb is manufactured from a conductive carbon resin composite.
  • the separator lb is formed with fuel gas manifolds 2a, 3a, oxidant gas manifolds 2b, 3b, and coolant manifolds 2c, 3c allowing fuel gas, oxidant gas, and coolant to flow respectively in the stacking direction of the fuel cell stack 10.
  • Each manifold serves as either a fluid supply manifold or a fluid discharge manifold.
  • the separator lb is provided with a plurality of oxidant gas passages 4b bifurcating from the manifold 2b and extending to the oxidant gas discharge manifold 3b.
  • Ribs 5b having a convex cross section and contacting the gas diffusion electrode lp to realize a current collecting function are provided between the passages 4b.
  • the width of the passages 4b increases in stages from the end parts of the surface of the separator lb toward the center. In addition, the width of the passages 4b increases and the width of the ribs 5b decreases toward the downstream side (the right side of the drawing).
  • temperature distribution over the cell surface is uneven such that the temperature near the center, where it is difficult for reaction heat to dissipate, is high.
  • This gas temperature differential on the surface causes differences to arise in the expansion factor and saturation vapor pressure, leading to a reduction in the mass flow of the oxidant gas flowing near the center. This tendency is particularly striking in high current density regions.
  • the constitution described above enables the oxidant gas to flow through the passages 4b near the center of the separator more easily than it flows through the passages 4b existing on the outer sides, and hence the gas diffusion near the center can be improved. Furthermore, in the downstream region where the oxidant gas concentration of the oxidant gas decreases due to an electrode reaction, the ribs 5b decrease in width, and thus in the downstream region, the surface contact area between the oxidant gas and the gas diffusion electrode lp increases, thereby improving the gas diffusion. Hence according to this embodiment, reductions in current density accompanying a decreased mass flow near the center of the cell surface can be suppressed, and reductions in current density caused by a decrease in concentration can be prevented even in the downstream area of the reactant gas.
  • the width of the passages 4b is increased in stages.
  • the width of the passages 4b may be increased gradually.
  • the reason for altering the width of the passages 4b is to increase the sectional area of the passages 4b, and therefore instead of, or in addition to, altering the width of the passages 4b, the depth of the passages 4b may be altered.
  • the width of the ribs 5b is reduced in the downstream region of the passages 4b as described above, but other than reducing the width of the ribs 5b, the ribs 5b may be formed in a lattice form or the like to reduce the surface area of the ribs 5b contacting the gas diffusion electrode lp and increase the surface contact area between the oxidant gas and the gas diffusion electrode lp. Moreover, a similar constitution may be applied to the separator lc on the fuel gas side as well as the separator lb on the oxidant gas side.
  • FIG. 7 shows the constitution of a fuel cell stack according to a fifth embodiment.
  • the fuel cell stack 10 comprises a plurality of stacked unit cells 11.
  • the basic constitution of the unit cell 11 is identical to that shown in FIG. 1A, comprising the membrane electrode assembly la, the fuel gas separator lc, and the oxidant gas separator lb provided with coolant passages on its rear surface.
  • End plates 12 which also provide a current collecting function are disposed on the two end parts.
  • the oxidant gas separator lb used in the plurality of fuel cells 11 positioned near the center in the stacking direction (the section shaded with diagonal lines in FIG. 7) is identical to the oxidant separator lb shown in FIG.
  • the oxidant gas separator lb used in the other stacked positions is also identical to the oxidant separator lb shown in FIG. 5 when seen from above, but the passages 4b are comparatively shallow, for example 0.45mm.
  • the stacked unit cells 11 if the unit cells disposed in the center are assumed to constitute a first region and the unit cells 11 disposed on the outer sides of the unit cells 11 disposed in the center are assumed to constitute a second region, then the temperature of the first region is higher than that of the second region.
  • the width of the passages 4b adjacent to the first region is greater than the width of the passages 4b adjacent to the second region, and hence the passages 4b adjacent to the first region have a larger sectional area.
  • temperature distribution in the stacking direction is uneven such that the temperature of the unit cells 11 positioned near the center, where heat dissipation is difficult, increases. This temperature difference causes differences to arise in the expansion factor and saturation vapor pressure, leading to a reduction in the mass flow of the oxidant gas flowing through the oxidant gas separators of the unit cells 11 positioned near the center. This tendency is particularly striking in high current density regions.
  • oxidant gas flows through the oxidant gas separators in the unit cells 11 positioned near the center in the stacking direction more easily than it flows through the oxidant gas separators in the unit cells 11 existing in the other stacked positions.
  • the gas diffusion in the unit cells 11 positioned near the center of the fuel cell stack 10 in the stacking direction is improved over the gas diffusion of the unit cells 11 in the other stacked positions, enabling reductions in the cell voltage caused by decreased mass flow to be suppressed.
  • a fuel cell stack exhibiting stability and high performance, and having a uniform cell voltage distribution even under operating conditions in which diffusion limiting is likely to occur, such as high current density in particular, can be obtained.
  • the depth of the passages 4b in the separator lb is varied according to the stacked position in the fuel cell stack 10, but instead of, or in addition to, varying the depth of the passages 4b, the sectional area of the passages 4b may be varied. Further, the depth of the passages 4b is varied between the plurality of unit cells 11 positioned near the center of the fuel cell stack 10 in the stacking direction and the unit cells 11 positioned in the other parts, but the depth of the passages 4b may be increased gradually from the end parts toward the center. Moreover, this constitution may be applied to the fuel gas side as well as the oxidant gas side.
  • the basic constitution of a fuel cell according to a sixth embodiment of this invention is similar to that of the fifth embodiment shown in FIG. 7.
  • the fuel cell stack 10 of this embodiment differs from the fifth embc>diment in the constitution of the oxidant gas separator lb used in the plurality of unit cells 11 positioned near the center in the stacking direction (the section shaded by diagonal lines in FIG. 7).
  • the constitution of the oxidant gas separator used in the other stacked positions (the non-shaded parts of FIG. 7) is identical to that of the oxidant gas separator lb shown in FIG. 5.
  • the constitution of the oxidant gas separator lb used near the center of the stacking direction is shown in FIG. 8.
  • the difference between the oxidant gas separators in FIG. 8 and FIG. 5 is that the oxidant gas passages 4b and the ribs 5b of the oxidant gas separator lb in FIG. 8 are narrower than those of the separator in FIG. 5. It should be noted, however, that the depth of the passages 4b is the same in both separators, and the total sectional area of all of the passages 4b existing on the surface of a single gas separator lb is the same in both FIG. 8 and FIG. 5. In the fuel cell stack 10, temperature distribution in the stacking direction is uneven such that the temperature of the unit cells 11 positioned near the center, where heat dissipation is difficult, increases.
  • the constitution of the oxidant gas separators in the plurality of unit cells 11 positioned near the center of the stacking direction differs from that of the unit cells 11 positioned in the other parts, but the constitution of the oxidant gas separators may be varied gradually toward the center.
  • the constitution of this embodiment may be applied to the fuel gas side as well as the oxidant gas side.
  • the basic constitution of a fuel cell according to a seventh embodiment of this invention is similar to that of the fifth embodiment shown in FIG. 7.
  • the constitution of the oxidant gas diffusion electrode lp differs in the plurality of unit cells 11 positioned near the center of the stacking direction (the section shaded by diagonal lines in FIG. 7) and the plurality of unit cells 11 positioned on the end sides (the non-shaded parts of FIG. 7). More specifically, the coating thickness of the carbon-Teflon mixture that is coated onto the surface of the carbon paper constituting the oxidant gas diffusion electrode lp is different near the center of the stacking direction and on the end sides.
  • the mixture is coated more thinly onto the gas diffusion electrodes lp of the fuel cells 11 near the center than the gas diffusion electrodes lp of the fuel cells 11 on the end sides. It should be noted, however, that the specification of the catalyst layer coated onto the mixture is the same in both cases. Moreover, the constitution of the oxidant gas separator is identical to that shown in FIG. 5. In the fuel cell stack 10, temperature distribution in the stacking direction is uneven such that the temperature of the unit cells 11 positioned near the center of the stacking direction, where heat dissipation is difficult, increases.
  • This temperature difference causes differences to arise in the expansion factor and saturation vapor pressure, leading to a reduction in the mass flow of the oxidant gas flowing through the oxidant gas separators of the unit cells 11 positioned near the center. This tendency is particularly striking in high current density regions.
  • the porosity of the oxidant gas diffusion electrode increases toward the center of the stacking direction, leading to improved gas diffusion near the center of the stacking direction.
  • the constitution of the oxidant gas diffusion electrode lp differs in the plurality of unit cells 11 positioned near the center of the stacking direction and the unit cells 11 positioned in the other parts, but the constitution of the oxidant gas diffusion electrode lp (the coating thickness of the mixture) may be altered gradually from the end parts toward the center.
  • the porosity of the gas diffusion electrode lp is changed by altering the thickness of the mixture.
  • another method for example changing the porosity of the gas diffusion electrode lp by not coating the rnixture onto the gas diffusion electrodes used near the center of the stacking direction or the like, may be employed.
  • this constitution may be applied to the fuel gas side as well as the oxidant gas side.
  • the basic constitution of the fuel cell stack 10 according to an eighth embodiment of this invention is similar to that of the fifth embodiment shown in FIG. 7.
  • the constitution of the oxidant gas separators used in the plurality of unit cells positioned near the center of the stacking direction is similar to that of the fourth embodiment shown in FIG. 6, and the oxidant gas passages 4b are comparatively deep, for example 0.50mm.
  • the constitution of the oxidant gas separators used in the unit cells 11 positioned at the end sides is also similar to the constitution shown in FIG. 6, but the passages 4b are comparatively shallow, for example 0.45mm.
  • the passages 4b are wide and the ribs 5b are narrow.
  • temperature distribution over the cell surface is uneven such that the temperature near the center, where heat dissipation is difficult, increases.
  • This surface temperature difference of the gas causes differences to arise in the expansion factor and saturation vapor pressure, leading to a reduction in the mass flow of the oxidant gas flowing near the center. This tendency is particularly striking in high current density regions.
  • the gas passages 4b by constituting the gas passages 4b as described above, the oxidant gas flows more easily in the vicinity of the center, and hence the gas cliffusion near the center can be improved.
  • the ribs 5b decrease in width, and thus in the downstream region, the surface contact area between the oxidant gas and the gas diffusion electrode lp increases, enabling an improvement in the gas diffusion.
  • temperature distribution in the stacking direction is uneven such that the temperature of the unit cells 11 positioned near the center, where heat dissipation is difficult, increases. This temperature difference causes a reduction in the mass flow of the oxidant gas flowing through the oxidant gas separators of the unit cells 11 positioned near the center. This tendency is particularly striking in high current density regions.
  • the depth of the oxidant gas passages 4b is different near the center and at the end sides as described above, and thus the oxidant gas flows more easily through the unit cells 11 near the center.
  • the gas diffusion can be improved near the center.
  • reductions in current density accompanying decreased mass flow near the center of the cell surface can be suppressed, and irregularities in the current density caused by decreased concentration can be prevented even in the downstream region of the reactant gas.
  • Reductions in cell voltage caused by decreased mass flow in the unit cells 11 positioned near the center of the stacking direction can also be suppressed.
  • a fuel cell stack exhibiting stability and high performance can be obtained even under operating conditions in which diffusion lirniting is likely to occur, such as a high current density operation or an operation with high reactant gas utilization.
  • the gas diffusion over the surface can be offset.
  • the gas passage form and rib form do not have to be altered, and any constitution that can offset the gas diffusion over the surface may be employed.
  • the constitution of the oxidant gas separator is altered in stages between the plurality of unit cells 11 positioned in the center of the stacking direction and the unit cells 11 positioned in the other parts, but the constitution of the oxidant gas separator may be altered gradually from the ends of the stacking direction toward the center. Moreover, the constitution of this embodiment may be applied to the fuel gas side as well as the oxidant gas side.
  • the entire contents of Japanese Patent Application P2003-410509 (filed December 9, 2003) are incorporated herein by reference.
  • This invention may be applied to a fuel cell stack to suppress reductions in cell voltage caused by decreased mass flow in high temperature regions, and thus improve the performance of the fuel cell stack.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Fuel Cell (AREA)
  • Inert Electrodes (AREA)

Abstract

L'invention concerne un empilement de piles à combustibles (10). Ledit empilement comprend une pluralité de piles unitaires empilées (11). Chaque pile unitaire (11) comprend un ensemble électrode-membrane (1a) et des séparateurs (1b, 1c) présentant des nervures (5b) qui entrent en contact avec l'ensemble électrode-membrane (1a) afin d'assurer une fonction de collecte de courant, ainsi que des passages de gaz (4b) formés entre les nervures (5b) afin d'alimenter un gaz vers une électrode de diffusion de gaz (1p). L'intérieur de l'empilement de piles à combustibles (10) comprend une première région et une seconde région présentant une température inférieure à la première région. Un quelconque élément parmi les passages de gaz (4b), les nervures (5b) et l'électrode de diffusion de gaz (1p) est constitué de telle sorte que la diffusion de gaz à travers l'électrode de diffusion de gaz (1p) adjacente à la première région est améliorée au-delà de la diffusion de gaz à travers l'électrode de diffusion de gaz (1p) adjacente à la seconde région.
PCT/JP2004/017892 2003-12-09 2004-11-25 Empilement de piles a combustible WO2005057697A2 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US10/582,222 US20070105001A1 (en) 2003-12-09 2004-11-25 Fuel cell stack
DE112004002438T DE112004002438T5 (de) 2003-12-09 2004-11-25 Brennstoffzellenstapel
CA2548296A CA2548296C (fr) 2003-12-09 2004-11-25 Assemblage de piles a combustible supprimant les reductions de densite de courant dans une region a haute temperature

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2003-410509 2003-12-09
JP2003410509A JP2005174648A (ja) 2003-12-09 2003-12-09 燃料電池

Publications (2)

Publication Number Publication Date
WO2005057697A2 true WO2005057697A2 (fr) 2005-06-23
WO2005057697A3 WO2005057697A3 (fr) 2007-07-05

Family

ID=34674940

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2004/017892 WO2005057697A2 (fr) 2003-12-09 2004-11-25 Empilement de piles a combustible

Country Status (6)

Country Link
US (1) US20070105001A1 (fr)
JP (1) JP2005174648A (fr)
CN (1) CN100546082C (fr)
CA (1) CA2548296C (fr)
DE (1) DE112004002438T5 (fr)
WO (1) WO2005057697A2 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
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EP1968149A1 (fr) * 2007-03-02 2008-09-10 Siemens Aktiengesellschaft Unité de piles à combustible
EP2330668A1 (fr) * 2008-09-12 2011-06-08 Panasonic Corporation Pile à combustible à membrane électrolytique polymère, et empilement de piles à combustible
US8173317B2 (en) * 2006-11-08 2012-05-08 Hitachi, Ltd. Fuel cells power generation system
FR3033667A1 (fr) * 2015-03-09 2016-09-16 Snecma Empilement ameliore pour pile a combustible pour l'etablissement d'un debit homogene

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JP4989080B2 (ja) * 2006-02-07 2012-08-01 本田技研工業株式会社 燃料電池
JP5098212B2 (ja) * 2006-04-27 2012-12-12 日産自動車株式会社 燃料電池
JP2008010179A (ja) * 2006-06-27 2008-01-17 Toyota Motor Corp 燃料電池セパレータ
KR100891356B1 (ko) 2007-12-06 2009-04-01 (주)퓨얼셀 파워 연료전지 분리판 및 이를 구비한 연료전지 스택
EP2362470B1 (fr) * 2008-12-02 2014-05-21 Panasonic Corporation Pile à combustible
JP5180946B2 (ja) 2009-11-26 2013-04-10 本田技研工業株式会社 燃料電池
JP2012190746A (ja) * 2011-03-14 2012-10-04 Denso Corp 燃料電池スタックおよび燃料電池
CN102637884A (zh) * 2012-04-27 2012-08-15 中国东方电气集团有限公司 双极板、冷却板及燃料电池堆
US9876238B2 (en) * 2012-06-05 2018-01-23 Audi Ag Fuel cell fluid channels
JP5699262B2 (ja) * 2013-05-02 2015-04-08 バラード パワー システムズ インコーポレイテッド 燃料電池プレートの流れ場
JP6898188B2 (ja) * 2017-09-15 2021-07-07 森村Ｓｏｆｃテクノロジー株式会社 燃料電池スタック
JP6874724B2 (ja) * 2018-03-28 2021-05-19 トヨタ自動車株式会社 燃料電池
EP4181243A3 (fr) * 2021-11-12 2023-05-31 Bloom Energy Corporation Interconnexion de piles à combustible optimisée pour un fonctionnement dans un combustible à hydrogène

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JP2003132911A (ja) * 2001-10-25 2003-05-09 Toyota Motor Corp 燃料電池

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8173317B2 (en) * 2006-11-08 2012-05-08 Hitachi, Ltd. Fuel cells power generation system
EP1968149A1 (fr) * 2007-03-02 2008-09-10 Siemens Aktiengesellschaft Unité de piles à combustible
WO2008107358A1 (fr) * 2007-03-02 2008-09-12 Siemens Aktiengesellschaft Unité pile à combustible
EP2330668A1 (fr) * 2008-09-12 2011-06-08 Panasonic Corporation Pile à combustible à membrane électrolytique polymère, et empilement de piles à combustible
EP2330668A4 (fr) * 2008-09-12 2013-01-16 Panasonic Corp Pile à combustible à membrane électrolytique polymère, et empilement de piles à combustible
US8691471B2 (en) 2008-09-12 2014-04-08 Panasonic Corporation Polymer electrolyte fuel cell and fuel cell stack comprising the same
FR3033667A1 (fr) * 2015-03-09 2016-09-16 Snecma Empilement ameliore pour pile a combustible pour l'etablissement d'un debit homogene

Also Published As

Publication number Publication date
US20070105001A1 (en) 2007-05-10
JP2005174648A (ja) 2005-06-30
CA2548296A1 (fr) 2005-06-23
CN101069311A (zh) 2007-11-07
DE112004002438T5 (de) 2008-03-06
CN100546082C (zh) 2009-09-30
CA2548296C (fr) 2010-06-01
WO2005057697A3 (fr) 2007-07-05

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